Suction box cover for papermaking machines



March 6,. 1951y D R, R0BB|N5 2,543,870

SUCTION BOX COVER FOR PAPERMAKING MACHINES Filed Dec. 10, 1947 z l I I l l I l1 I l WWII* "hmm 1716.1.

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Patented Mar. 6, 1951 UNITED STATES PATENT OFFICE SUCTION BOX COVER FOB PAPERMAKING MACHINES 7 Claims.

This invention relates to suction box covers for paper making machines. It is conventional in connection with modern paper making machines, to provide suction boxes transversely of the web of the paper being made and disposed under the screen in order to remove excess water from the stock.

In most paper making machines there are a number of such transverse suction boxes. 'I'hs invention is directed specifically to covers for such suction boxes in connection with which a number of problems present themselves for solution.

It is desirable that the perforations in the suction box cover` give complete coverage so that water may be abstracted from all portions of the web. It is also desirable that there not be long elements of the web which are unsupported by the suction box cover. The suction box cover should be relatively easy and inexpensive to manufacture and should not cause excessive wear on the material of the screen which passes over it.

There have been in the past suction box covers having straight slots extending entirely across the web. These covers have given complete coverage which is of very great importance, but they have left long portions of the screen and the web thereon unsupported, so that excessive wear has resulted on the edges of the slots as well as on the knuckles of the wire, which with the repeated flexing of the wire resulted in rapid wear. Another type of suction box cover has been provided with what is known as herringbone 'slots and these have been objectionable because they have left a considerable length of the web in the direction of motion unsupported. Attempts have also been made to provide suction box covers with circular drilled holes, but it has been found that such suction box covers are extremely diflicult and expensive to manufacture because of the need for precision.

With the above considerations in mind, it is an object of my mention to provide a suction box cover which eliminates the disadvantages and objections set forth above. It is therefore an object of my invention to provide a suction box cover which is easier to make and which can be made much less expensively. An object of my invention resides in the provision of a suction box cover which will give complete coverage over the width of the web so as to insure an even and uniform evacuation.

It is yet another object of my invention to provide a suction box cover in which the evacuation slots are echeloned and in which the echelons are lateral thrust on the screen.

A still further object of my invention involves the provision of a suction box cover of a material which to some extent absorbs moisture so as to have a lubricating eiect upon the screen which passes over it.

Yet another object of my invention includes the provision of a sectionalized suction box cover so that the cover may be manufactured in unit sections, and so that any desired number of sections may be placed end to end, depending upon the width of the machine. In this connection an ancillary object is to provide a construction whereby the evacuating effect in the region of the joints is not changed with respect to the evacuating eifect between joints.

These and other objects of my invention which will .be set forth in more detail hereinafter or which will become apparent to one skilled in the l art upon reading these specifications, I accomplish by that certain construction and arrangement of parts of which I shall now describe an exemplary embodiment.

Reference is made to the drawings forming a parthereof and in which- Figure l is a plan view of a suction box cover unit. Y

Figure 2 is a cross sectional view of the same taken on line 2--2 of Figure l.

Figure 3 is a cross sectional view of the same taken on the line 3--3 of Figure l and Figure 4 is a cross sectional View through a portion of a paper making machine showing two suction boxes with their covers in place thereon and with a screen and paper web passing thereover.

Since this invention has to do only with the suction box cover itself, the suction boxes and other details of the paper making machine will not be described except in connection with the more or less diagrammatic view of Figure 4, in which I have shown a Fourdrinier screen IIJ, carrying a web of partially formed paper I I passing over the suction boxes I2, of which I have shown only 2. Many paper making machines of course will have morey than two suction boxes. Suitable means are provided for drawing air through the suction boxes in the direction of the arrows so as to draw water out of the web II. Each suction box is provided with a cover indicated generally at I3, which provides a supporting cover for the screen I0 as it travels over the suction box and which is provided with apertures of one'form or another for the passage of water.

Coming now to a description of the Particular suction box cover of my invention, I prefer to make the same of a monolithic homogeneous material. This material is a dried shredded material consisting of vegetable fibers impregnated with a resin which, under heat and pressure, iiows and cures into a hard monolithic homogeneous slab. In manufacturing a suction box cover according to my invention, I provide a suitable cored mold and place the dry, shredded resin impregnated vegetable fibers therein and then cure the slab under heat and pressure.

The suction box cover I3 is provided with a number of slots I4 which slots are tapered as best seen in Figures 2 and 3 so that they are outwardly toward the bottom. This construction tends to prevent fouling of the slots during a paper making operation. It is desirable to provide as much taper for these slots as is consistent with adequate strength. I have found a satisfactory taper to be about 11;" where the slot is about 1%" thick.

In'order to provide for complete coverage and yet to avoid continuous lines in the direction of motion of the screen, I dispose the slots I4, in two groups indicated by the brackets I5 and I6, and I echelon the slots in each of these groups oppositely so that, for example,`in Figure 1 the slots of group I5 are echeloned to the left and the slots in group I6 are echeloned to the right. The purpose of this opposite echeloning is to neutralizeA any lateral thrust upon the screen, it being understood that the direction of travel of the screen in Figure l is vertical. Furthermore, I dispose the slots in the two groups so that the lowermostrow of slots in lgroup I5 is in vbreak-joint relationship with -the'uppermost row of slots of group While the slots themselves may be rectangular in plan view,- I prefer tomake them rhomboid in shape so as to avoid longitudinal lines in the direction of movement of the screen. v

It will be noted that the Obliquity of the rhomboids is in the samedirection and of the same degree as the echeloning of the slots. Thus the lateral ends of a group of vslots in the group I5 are aligned and similarly the lateral ends of a series of slots in the group I6 are aligned.

While I have shown four rows'of slots in each of groups I5 and I 6, this doesnotconstitutea f the same row divided. by the'numbr of rows.

Thus, considering the lower lefthand'corners of the slots in group )I6 and the upper left-hand.

tion of the number of rows of slots and the distance between slots in a row.

For the sake of simplicity, I have shown the suction box cover unit of Figure l, as having its side edges cut of! at right angles 'w its length. This, of course, would produce a line of demarkation in the directiony of travel of the screen, and it will be clear that this may be avoided by cutting the edges of the unit Il at an angle. I have, however,-shown the right angle coniguration to illustrate how an adjacent unit may be placed against the unit I3 to complete the partial slots in the edges thereof, so that a complete suction box cover may be made, of any desired number of such units. It is only necessary that the cuts be at pattern repeat points or a multiple thereof.

From the foregoing description, it will be apparent that numerous variations in the pattern may be made without departing from the fundamental principles set forth which result in complete coverage and uniform evacuation. According to my invention, the amount of suction in the direction of travel is substantially identical for any longitudinal element at any position transversely of the web. For example, in following the broken line w-w it will be observed that it intersects six complete slots, and that the sected will still be six in this particular arrangement.

For 'the foregoing reasons, I do not desire to limit myself-to the specic arrangement shown except insofar as is set forth in the claims whichv verserows of transverse slots, there being an equal number of rows in each group, the slots in the rows of said two groups being oppositely y echeloned and each slot in any row being out of corners of thev slots ingroup- I5,which correspond to each other, the pattern repeat point is, for; ex-l` l. ample, at d' and i. It willgbeobservedgthatzthe L Thus it will be' observed thatmyresultinayf be attained regardlessfof thejnumber of4 rows line, longitudinally of said machine, with every other slot. v

2.` A rdevice according to claim l, in which said slots are of rhomboid shape, and in which the Obliquity of said rhomboids is in the same direction and of the same degree as the echeloning vof said slots.

' 3. A device according to claim 2,'in which the displacement of a slot in one row in echelon with respect .to the corresponding slot in an adjacent r`in'gpoints onl adjacent slots in the same row,

"divided'by' the number of rows.

chines; comprising a slab arranged to 'be mount- '.'on a vsuction box transversely of said machine, said` slab being provided with two groups of transver'sejrows of transverse slots, there being an L1 equal number of rows in each group, the slots -in the'rows of said two groups being oppositely echeloned' and each slot in any row being out of line, longitudinally of said machine, with every A.other slot, the lateral ends of said slab occurring at corresponding pattern repeat points and being of slots, because the obliquity of the rhomboid shapes thedegree` of echeloning are affanc- Q parallel, whereby a plurality of slabs may be laid :end 1 to end to constitute a suction box cover.

tinuous line in the direction oi travel of a paper web.

6. A suction box cover for paper making machines, comprising a slab arranged to be mounted on a suction box transversely of said machine, said slab being provided with two groups of transverse rows of transverse slots, there being an equal number of rows in each group, the slots in the rows of said two groups being oppositely echeloned and each slot in any row being out of line, longitudinally of said machine, with every other slot, said slab being hard and monolithic such as is produced by curing resin impregnated vegetable fibers under heat and pressure.

7. A suction box cover for paper making machines, comprising a slab arranged to be mounted on a suction box transversely of said machine, said slab being provided with two groups of transverse rows of transverse slots. there being an equal number of rows in each group, the slots in the rows of said two groups being oppositeiy echeloned and each slot in any row being out oi' line, longitudinally of said machine, with every 6 other slot, said slab being constituted of a material capable of absorbing water,1 whereby to be self lubricating with respect to a paper making screen passing thereover.

DOUGLAS R. ROBBINS.

REFERENCES CITED The following references are of record in the le of this patent:

UNITED STATES PATENTS Number Name Date 708,219 Gilbert et al Sept. 2, 1902 751,095 McAnulty Feb. 2, 1904 920,100 Whisner Apr. 27, 1909 1,236,359 Reynolds Aug. 17, 1917 1,832,844 Cofrin Nov. 24.1931

2,010,150 Hemphill Aug. 6, 1935 2,042,198 Swauger May 26. 1936 2,346,785 Proulx Apr. 18, 1944 l FOREIGN PATENTS Number Country Date 141,045 Austria Mar. 11, 1935 

